1. Field of the Invention
The present invention relates to an information processing technique of saving a file change log and restoring a state before change, as needed.
2. Description of the Related Art
Recently, various kinds of information processing apparatuses capable of installing and executing arbitrary applications, including a personal computer (to be referred to as a PC hereinafter) and a personal digital assistant (to be referred to as a PDA hereinafter), are becoming popular in every field such as business, education, and household. Users daily browse and edit a variety of data such as videos, photos, documents, and graphics by using these applications.
Under these circumstances, various techniques of managing, for example, a data edit log and freely restoring the initial state have been proposed to improve the convenience of user's edit operations on applications.
For example, a general application has a restoring function called “undo” to cancel preceding data edit operations within a predetermined range and restore previous data. The restoring function is disclosed in detail in, for example, “Microsoft® Office Training: A Guide to Word 2003”, U.S. Microsoft Corporation, http://office.microsoft.com/training/Training.aspx?Asse tID=RP010736521041&CTT=6&Origin=RC010736361041.
Japanese Patent Laid-Open No. 09-026905 proposes a technique of allowing a user to return updated data to previous contents at an arbitrary point in time in the past without being conscious of data saving/management. More specifically, this technique is implemented by imparting a difference storage means to an operating system (OS) and storing updated file contents as difference log information. According to this reference, when a user designates a date/time to restore a file, the file at the designated date/time is restored by referring to the file and difference log information.
However, if each application has a restoring function, as described above, and the restoration count and reset conditions change between the applications, the user may be confused. In some cases, data that the user has considered restorable cannot be restored.
The arrangement of Japanese Patent Laid-Open No. 09-026905, which adds the difference storage means to the OS and restores a file by referring to difference log information based on a restoration date/time, does not depend on any application and therefore can avoid such situations. In this technique, however, the user himself/herself must remember the date/time when the state to be restored is saved, resulting in inconvenience for the user.